"We can go back and print ballot papers as many times as needed, we have the electoral roll, ballot boxes and there will be polling stations," he told AFP this week.

The most probable scenario is that voting will take place around Catalonia, though in a haphazard way.

"They will attempt to organise a simulation of a vote, and we will see how well it is followed and with what capacity," says Miquel Iceta, leader in Catalonia for the Socialist Party, which is against the referendum.

- Fear of unrest -

Students take part in a pro-referendum demonstration called by students on September 28, 2017 in Barcelona

Josep LAGO, AFP

Catalan police warned Wednesday that public disorder may erupt over orders to guard polling stations and stop people from entering.

Such a step "could lead to undesirable consequences," the Mossos d'Esquadra said on Twitter.

"These consequences refer to public security and to the more than foreseeable risk of a disruption of public order that this may generate."

On Thursday, both Catalonia's regional interior minister Joaquim Forn and Jose Antonio Nieto, number two at Spain's interior ministry, called for whatever happens to take place in a "peaceful" manner.

- Negotiations -

As it looks certain that Catalans will go vote in one form or another -- and that the 'Yes' will win given 'No' supporters won't turn out -- Catalonia's separatist leaders will likely capitalise on this.

But how?

The first option, according to Gabriel Colome, politics professor at the Autonomous University of Barcelona, would be to decide not to proclaim independence as they had promised in a law passed by the majority separatist Catalan parliament.

Already the CGT union has called a regional strike for Tuesday to protest against "the general suspension of civil rights experienced over the past days."

It remains to be seen if the UGT and CCOO unions -- Spain's largest -- follow suit.

A protracted strike could severely damage Spain.

Catalonia is one of the powerhouses of the Spanish economy, contributing 19 percent of the country's GDP.

Under this scenario, "what they want is to negotiate," says Colome, on matters of autonomy and financing, and Madrid has indicated it will be willing to talk.

A national parliamentary commission has been created by the Socialists to debate changes in the status of Spain's regions on the back of the crisis.

And one of Catalonia's separatist parties, PDeCat, has accepted to take part.

This could be a hint that at least part of Catalonia's ruling coalition is seeking negotiations.

- Proclamation? -

The other option, says Rafael Arenas Garcia, a law professor at the Autonomous University of Barcelona, is that Catalan President Carles Puigdemont makes a unilateral declaration of independence.

Madrid would have to react.

"The consequences will be proportionate," Enric Millo, the central government's representative in Catalonia, warned Tuesday.

How strong though? Madrid has the power to take away autonomy from Catalonia, for instance, by taking control of the regional police.

It could also detain Puigdemont himself, an image that would go round the world.

This would play into the hands of separatist leaders, who hope to "automatically turn those who were undecided... and change the logic of independence into the logic of defending democracy against a repressive state," says Colome.

- Elections? -

The third scenario post-vote is that the separatists will not declare independence but dissolve at some point the Catalan parliament, which would lead to early regional elections.

Separatist leaders will be hoping that the recent crisis will have rallied more people to their cause, giving them an even bigger parliamentary majority to continue to fight for independence.